Use Of GA3 Research Articles

Métodos para superação de dormência em sementes de tomateiro arbóreo (Solanum betaceum)

RESUMO O tomateiro arbóreo (Solanum betaceum) é espécie pouco conhecida, porém, apresenta frutos com enorme potencialidade de mercado, uma vez que podem ser consumidos tanto in natura como na forma industrializada. Contudo, um dos entraves para essa potencialidade se tornar realidade é a produção de mudas. A propagação dessa espécie ocorre por meio de sementes, mas, normalmente, a germinação requer tempo, principalmente sob condições de estresse. Objetivou-se verificar se existe dormência em sementes de tomate arbóreo e a técnica adequada para obter germinação rápida e uniforme. O delineamento foi o inteiramente casualizado, em esquema fatorial 5 x 2 (métodos para superação de dormência x luz), com 4 repetições de 50 ou 60 sementes, de acordo com o ciclo produtivo. Os métodos avaliados foram estratificação, hidrocondicionamento, condicionamento osmótico com GA3 e controle, com e sem luz. Também foram avaliados a germinação e o índice de velocidade de germinação, bem como o início e tempo médio de germinação. A utilização de GA3 na concentração de 100 mg L-1 ou 300 mg L-1 é recomendada para a germinação de sementes de tomate arbóreo.

Improving seed germination of the eggplant rootstock Solanum torvum by testing multiple factors using an orthogonal array design

Solanum torvum is a highly vigorous relative of eggplant that is resistant to a number of harmful soil-borne diseases and is compatible for grafting with eggplant. Being a potential rootstock, this plant frequently presents poor and erratic germination, which makes its practical use difficult. We used an L8 (27) orthogonal array design to evaluate the primary effects of seven factors (soaking of seeds, scarification with sodium hypochlorite (NaClO), application of gibberellic acid (GA3), use of potassium mitrate (KNO3) as a moistening agent, cold stratification, application of a heat shock, and light irradiation during germination) at two levels (L0 and L1) using four germination parameters (early and final germination, germination rate and vigour index) in fresh S. torvum seeds. S. torvum seeds had a strong dormancy with no germination in the untreated seeds and high early and final germination (approximately 100%) in certain treatments. An evaluation of the main effects revealed highly positive effects on germination from seed soaking, and the use of GA3, KNO3, and light irradiation, whereas NaClO scarification had a negative effect. The application of cold stratification and heat shock treatments also had a positive effect on seed germination but to a lesser extent than the other treatments. An improved proposed protocol that consisted of subjecting seeds to soaking, the application of GA3 and KNO3, cold stratification, heat shock, and light irradiation was validated and demonstrated to be highly effective, with seed germination success greater than 60% being observed at 3 days and final germination reaching a plateau at 6 days. A second validation experiment using a commercial growing substrate also showed a high emergence (approximately 50%) at 7 days and a final germination of approximately 80% was recorded with application of the improved protocol. The seed germination protocol that we have developed will facilitate the use of S. torvum as a rootstock for eggplant and its use in breeding programmes. Our results also reveal that orthogonal array designs are a powerful tool for establishing improved protocols for seed germination.

In vitro propagation of Cyrtopodium saintlegerianum rchb. f. (orchidaceae), a native orchid of the Brazilian savannah

In order to enable production of large quantities of plantlets for reintroduction programs, as well as economic exploration, Cyrtopodium saintlegerianum seeds were sown on Knudson culture medium. After seed germination, the protocorms were inoculated on Knudson culture medium supplemented with 6-benzyladenine (BA) and α-naphthaleneacetic acid (NAA). The obtained shoots were individually inoculated in Knudson supplemented with gibberellic acid (GA3) in order to promote elongation. Seedlings were evaluated and then transplanted into trays containing commercial substrate Plantmax(r)-HT, or crushed Acuri leaf sheath. Auxin/cytokinin ratio influenced in vitro propagation of C. saintlegerianum, resulting in increased shoot number when 2.0 mg L-1 BA was added to the culture medium in the absence or presence of 0.5 mg L-1 NAA. This species proved to be promising for massal in vitro multiplication. Despite having incremented in vitro shoots elongation, the use of GA3 is unnecessary since it contributed negatively in the acclimatization of plants.

Response of Okra (<i>Abelmoschus esculentus</i> L.) to Growth Regulators and Organic Manures

A study was conducted at the Horticulture Farm, Sher-e-Bangla Agricultural University, Bangladesh during April to September, 2012 to determine the suitability of selected plant growth regulators and the proper use and effectiveness of selected organic manures and also their suitable combinations for successful okra production. The experiment consisted of two factors: factor A: growth regulators as - G0: control (water), G1: GA3 (100 ppm) and G2: Miraculan (1000 ppm) and factor B: organic manures as - OM0: control (no manure), OM1: vermicompost (9 t/ha) and OM2: poultry manure (11.5 t/ha). The combined use of GA3 and poultry manure produced the tallest plants. Both the growth regulators and organic manures enhanced early flowering. In case of growth hormone, the highest yield (16.67 t/ha) was recorded from G1 followed by G2 (16.49 t/ha). The highest yield (18.03 t/ha) was found from OM2, closely followed by OM1 (17.59 t/h). Considering the treatment combinations, the highest yield was harvested from G1OM2 (19.62 t/ha), followed by G1OM1 (19.01 t/h), G2OM1 (18.42 t/h) and G2OM2 (18.30 t/h), respectively.The Agriculturists 2014; 12(2) 56-63

Effect of Various Pre-Treatments and Alternating Temperature on Seed Germination of Artemisia herba-alba Asso

The present study was designed to determine the effect of alternating temperature regimes (R) and pre-treatments on the achenes germination of Artemisia herba-alba Asso, in order to provide information about germination requirements to be used for the rehabilitation programs . Four alternating temperature regimes with a day-night cycle (16/8 h) were applied R1: (35-20 °C), R2: (30-15 °C), R3: (25-10 °C) and R4: (20-05 °C) and ten pre-treatments were tested for the best regime. This pre-treatments include the pre-soaking in cool water at two durations, pre-soaking in hot water for two durations, pre-soaking in sulphuric acid (0.1 Mol/l) for two durations, pre-soaking in GA3 (Gibberellic acid) for four hours at three concentrations (10 -5 M, 10 -4 M and 10 -3 M) and mechanical scarification with soft sandpaper. Temperature regimes affect significantly at the level 0.05 the final germination percentage and influence the germination rate. The R2 registered the best performances and the increase and the decrease of the temperature reduces the ability of seeds to germinate. Also, the application of the pre-treatments result in highly significant differences (p < 0.01) for the germination characteristics, basically the pre-soaking in cool water during 48h that gave the best overall percentage of germination (71%). The use of GA3 to promote germination was not significant as compared to control even at the highest concentration (10 -3 M).

New method for screening rice varieties against Bakanae disease

Several varietal screening methods were tested along with dipping dry seeds into millipore membrane filtrate of spore suspension of the pathogen and gibberellic acid (GA3) in different concentrations. It was found that GA3 can be used to screen out susceptible rice varieties against bakanae disease. The method which requires the use of GA3 is easier than the other methods for mass screening as it does not require maintaining living culture of the pathogen. The protocol of inoculum free varietal screening method for bakanae disease of rice was developed to find out resistant varieties from the huge collections of germplasm bank. DOI: http://dx.doi.org/10.3329/bjb.v42i2.18036 Bangladesh J. Bot. 42(2): 315-320, 2013 (December)

Water uptake and pre-germination treatments in macaw palm (Acrocomia aculeata - Arecaceae) seeds

The aims of this study were to evaluate the influence of embryo adjacent tissues in water uptake and treatments to release dormancy in macaw palm seeds. To assess water absorption with or without the opercular tegument (OT), seeds were immersed in water for 0, 12, 24, 48, 72, 96, 120, 168, 240, 360, 480 and 720 hours and the water content of isolated embryos and seeds was determined. In seeds with or without OT, gibberellic acid (GA3) solutions at concentrations of 0, 50, 100, 500, 1000 and 2000 mg.L-1 were applied on the OT region using a culture medium. In another experiment, the OT was removed or left intact and the seeds immersed in hydrogen cyanamide solutions (0, 0.5, 1, 1.5, 2 and 2.5%). The percentage germination, germination speed index (GSI) and percentage dead seeds were determined. The OT does not prevent embryo water uptake but reduces water absorption speed. The use of GA3 in a culture medium applied to the OT region did not effectively release dormancy. The use of cyanamide at these concentrations increased seed mortality, resulting in a low germination. OT removal increased the GSI.

Gibberellic Acid Sensitivity among Common Bean Cultivars (Phaseolus vulgaris L.)

To lower seed yield loss from directly harvested common bean or dry bean, height of the lower pod-bearing nodes needs to be raised. The objective of this greenhouse study was to stimulate lower stem elongation by gibberellic acid (GA3) of dry bean cultivars. Seeds of cv. Matterhorn, erect indeterminate Type II, and cv. Poncho, prostate indeterminate Type III, were dipped in GA3 at 62.5 to 16,000 ppm and planted. After 14 d, the height of the unifoliate and first trifoliate nodes showed maximum stimulation of stem elongation by 1000 ppm GA3 for ‘Poncho’ and by 2000 ppm for ‘Matterhorn’. Application of 1 mL of GA3 at 0.031 to 2048 ppm to newly expanded unifoliate leaves showed cultivar differences. Whereas ‘Matterhorn’ was promoted at 64 ppm and reached a maximum height by 512 ppm GA3, ‘Poncho’ was promoted at 0.25 ppm and reached a maximum height by 8 ppm GA3. Flowering of ‘Matterhorn’ was unaffected by GA3; flowering of ‘Poncho’ was completely inhibited by 128 ppm. The sensitivity difference of cultivars was verified with other cultivars. Type I cultivars, which are all determinate, showed a full range of GA3 sensitivity. Dry bean cultivars may be regrouped based on the GA3 dose to which they respond. Individual response to GA3 rates of dry bean cultivars needs to be predetermined using a short-term, 2–3 weeks, greenhouse bioassay before field use of GA3.

New perspectives of gibberellic acid production: a review

The gibberellins (GAs) are an important group of hormones which exert various effects on promoter and regulator of plant growth. Gibberellic acid (GA3) is a natural plant hormone, with great economical and industrial importance. It affects stem elongation, germination, elimination of dormancy, flowering, sex expression, enzyme induction and leaf and fruit senescence. Despite its diverse applications, the use of GA3 is limited due to its high production costs. The industrial process currently used for the production of GA3 is based on submerged fermentation (SmF) techniques. As an alternative for its production, solid state fermentation (SSF) has also been investigated for its ability to increase the yields of GA3 with the use of agro-industrial wastes as support/substrate, which contributes to the decreased production costs. This review describes GA3’s physical, chemical and biological properties, its production by fermentation and new advances that are being carried out with special interest on the SSF technique.

Identification and genetic mapping of elongated uppermost internode gene eui with microsatellite markers in rice (Oryza sativa L.)

Development of cytoplasmic male sterile (CMS) lines with elongated uppermost internode (EUI) trait is a desirable alternative to eliminate the use of GA3 in hybrid rice production. In this study, a simple and reliable PCR based, simple sequence repeats (SSR) markers was identified, for the eui gene to facilitate marker assisted selection (MAS). A total of 28 SSR markers, mapped in the vicinity of the genomic clone AC130605 (PD0010D04), were chosen for assessing the polymorphism between IR58025B and IR91-1591-3. A set of 151 F2 plants derived from the cross IR58025B/IR91-1591-3 were surveyed using 15 polymorphic SSR markers. Analysis using MAPMAKER 3.0 revealed that seven SSR markers viz., RM6054, RM3870, RM3476, RM5970, RM7801, RM7446 and RM3620 were linked with euilocus at the genetic distance ranging from 1.0 to 7.1 cM with EUI phenotype. Furthermore, these markers were validated in – F2 (IR58025A/IR91-1591-3) and backcross (IR58025B/IR91-1591-2//IR58025B) population segregating for euigene. The SSR markers reported in this study might be useful for the incorporation of eui gene into CMS lines of rice through marker-assisted backcrossing. Key words: Rice, cytoplasmic male sterility, elongated uppermost internode, microsatellites, marker assisted selection, panicle exsertion.

Soluções conservantes em sorvetão pós-colheita

O objetivo deste trabalho foi estudar alguns aspectos da fisiologia pós-colheita de inflorescências de sorvetão cultivadas no Submédio São Francisco. Hastes florais recém-colhidas foram submetidas a diferentes tratamentos (água destilada; 75mg L-1 de nitrato de prata - AgNO3; 1000mg L-1 de cloreto de cobalto - CoCl2; 5mg L-1 de ácido giberélico - GA3 - Progibb® e 10mg L-1 de 6-Benzilaminopurina - BAP), em ambiente com temperatura e umidade controlada por 15 dias. A vida pós-colheita foi acompanhada a partir da escala de notas, da massa da matéria fresca e do consumo da solução conservante. O tratamento com AgNO3 em hastes de sorvetão, foi o mais eficiente na manutenção da vida de vaso de sorvetão, porém, devido a sua toxidez, recomenda-se o uso de GA3.

Gibberellic acid, a plant growth regulator, increases mast cell recruitment and alters Substance P levels

Gibberellic acid (GA3), a plant growth regulator, is used commonly in agriculture. Its potential hazardous effects on human health, however, were relatively unexplored. Several studies demonstrated that in animals chronic GA3 consumption increased tumor formation and oxidative stress. Mast cells and Substance P (SP) play an important role in inflammation. Because chronic inflammation triggers serious conditions, including tumor formation, we examined changes in mast cell recruitment and activation as well as SP levels in skin and urinary bladder. Wistar Albino rats were treated with either a single GA3 dose or multiple GA3 doses for 30 days. Sub-chronic exposure to GA3 markedly increased mast cell recruitment and activation in both tissues. Treatment with 2 mg/kg GA3 dose for 30 days decreased SP levels in skin and bladder. SP levels returned to control values in bladder and further increased in skin following 30-day treatment with the 20 mg/kg GA3 dose. There was marked urothelial loss and inflammatory cell infiltration in bladder of 30-day GA3 treated groups. In skin, single GA3 doses also decreased SP levels and enhanced mast cell activation and recruitment. Since both SP and mast cell activation elicit inflammatory responses, these results demonstrate that exposure to plant growth regulators may increase inflammatory skin and bladder disease and that use of GA3 should be clearly monitored.

Isolation of Ligands of Trace Metals from Plant Samples by Immobilized Metal Affinity Chromatography

Isolation of ligands of trace elements from plants by affinity chromatography with a metal immobilised on iminodiacetate resin has been investigated. To simulate various types of bioligands the following compounds were tested: phytic acid, peptides containing Cys and peptides containing Asp. Optimal conditions allowing isolation of the peptides with good efficiency comprise the use of Ga3+ ion, sample adsorption at pH = 4 and elution of the compounds by 0.3 mol/l NH3. Phytic acid was bound too tightly and was not eluted. The procedure was used for purification of extracts of rye flour. The purified sample is suitable for analysis by MALDI-MS.

Micropropagation of Pongamia pinnata through enhanced axillary branching

A complete protocol is presented for the first time for the micropropagation of Pongamia pinnata, a biofuel tree, using cotyledonary nodes derived from axenic seedlings. Multiple shoots were induced in vitro from nodal segments through forced axillary branching. Murashige and Skoog (MS) medium supplemented with 7.5 μM benzylaminopurine (BAP) induced up to 6.8 shoots per node with an average shoot length of 0.67 cm in 12 d. Incorporation of 2.5 μM gibberellic acid (GA3) in the medium during the first subculture after establishment and initiation of shoot buds significantly improved the shoot elongation. Single use of GA3 during the first subculture eliminated the need for prolonged culturing on BAP medium. Further use of GA3 in the medium was not useful. Shoot culture was established for at least two subcultures without loss of vigor by repeatedly subculturing the original cotyledonary node on shoot multiplication medium followed by shoot elongation medium after each harvest of the newly formed shoots. Thus, from a single cotyledonary node, about 16–18 shoots were obtained in 60 d. Shoots formed in vitro were rooted on full-strength MS medium supplemented with 1.0 μM indole butyric acid (IBA). Plantlets were successfully acclimated, established in soil, and transferred to the nursery.

The effect of gibberellic acid on the in vitro germination of coconut zygotic embryos and their conversion into plantlets

The effect of gibberellic acid (GA3) was tested on germination of coconut zygotic embryos, their conversion into plantlets and ex vitro survival. There were four treatments consisting of 5 wk of culture in semi-solid medium or liquid medium, with or without GA3. Embryos were then transferred to GA3 free-liquid medium for the rest of a 32-wk culture. Germination and conversion percentages were higher in semi-solid medium than in liquid medium, and with both media percentages increased with GA3 treatment (with the exception of the highest GA3 concentration). Embryos of two varieties (MGD and MYD) were used. The following are the results with MGD embryos. Optimum GA3 concentration in liquid medium was 0.46 μM, with 80% germination (62% in the control without GA3) and 4.6 μM in semi-solid medium with 98% germination (71% in the control). With GA3 treatment, germination was also faster. Conversion in semi-solid medium with GA3 was 87% (60% in the control), and 45% in liquid medium with GA3 (25% in the control). Once the plantlets had at least three bifid leaves and three primary roots at the time of transfer to ex vitro, they survived independently of the treatment. When MYD embryos were used, germination and conversion percentages were higher in semi-solid medium than in liquid medium, and they increased when GA3 was used, although percentages were lower than those obtained with MGD embryos. The results showed that the use of GA3 benefited coconut embryos in culture because it favored germination and conversion to plants on semi-solid medium, and hence improved previous protocols.

Regulador vegetal e bioestimulante na indução floral do maracujazeiro-amarelo em condições de entressafra

O objetivo do trabalho foi avaliar o efeito de regulador vegetal e de bioestimulante na indução floral do maracujazeiro-amarelo em condições não-indutivas, em Araguari-MG. Foram identificados e podados 12 ramos terciários por parcela (02-04-05), sendo 6 deles expostos de um lado da espaldeira, com luminosidade predominante pela manhã e 6 do outro lado da espaldeira, com luminosidade à tarde. O delineamento experimental foi em parcelas subdivididas, com 7 tratamentos principais (parcelas): 0mg L-1 (testemunha); 100mg L-1; 200mg L-1 e 300mg L-1 de regulador vegetal GA3 (i.a.); 2,08 mL L-1; 4,17mL L-1 e 6,25mL L-1 de bioestimulante Stimulate® (i.a.), em duas aplicações foliares (09-04-02 e 09-05-02), acrescidas de espalhante adesivo Silwett® a 0,05%. Além desses, foram utilizados 2 tratamentos secundários (subparcelas): exposição dos ramos à luminosidade da manhã e da tarde, com 4 repetições de 3 plantas por parcela. Cada subparcela foi um dos dois lados da espaldeira. As médias foram comparadas pelo teste de Tukey, a 5% de probabilidade. Realizou-se, aos 75 dias, a avaliação nos dois lados da espaldeira do comprimento dos ramos e entrenós, número de nós, de folhas e de botões florais. As variáveis estudadas não foram influenciadas pelo uso de GA3 e Stimulate®, no entanto houve diferença quando os ramos ficaram expostos à luminosidade da manhã em relação àqueles com luminosidade à tarde.

Effect of Plant Growth Regulators on Growth, Yield and Quality of Chilli (&lt;i&gt;Capsicum annuum&lt;/i&gt; L.) at Rampur, Chitwan

The present investigation was carried out in the plain areas of Chitwan to determine the promising plant growth regulators (PGR) promoting growth and yield of chilli cultivars Jwala and Suryamukhi during winter-summer season of 2003/2004. Suryamukhi ranked superior to Jwala for most of the yield attributing characters, whereas Jwala was better in vegetative characters than Suryamukhi. Among PGRs, 2,4-D at 2 ppm was better for fruit set, number of fruits per plant, fruit length, number of seeds per fruit, seed weight per fruits, 1000 seed weight and fruit yield where as NAA at 40 ppm gave the highest leaf area index (LAI). PGRs were ineffective in promoting flowering and fruiting during winter season. GA3 at 10 ppm exhibited maximum amount of ascorbic acid content. The treatments, 2 ppm 2,4-D, 5 ppm triacontanol, 40 ppm NAA and 10 ppm GA3 produced 28.75%, 25.70%, 13.61% and 2.30% higher fruit yield over control, respectively. The highest net profit and B:C ratio were recorded in case of 2 ppm 2,4-D. The use of GA3 as foliar spray was not economical. &#x0D; &#x0D; Key words: 2,4-D, NAA, triacontanol, GA3, leaf area index, net profit, B:C ratio &#x0D; &#x0D; J. Inst. Agric. Anim. Sci. 27:65-68 (2006)

The influence of gibberellic acid and sulfur fertilization rate on growth and S-use efficiency of mustard (Brassica juncea)

Earlier research has shown that exogenous gibberellic acid (GA3) application increases shoot growth, photosynthesis and soil nitrogen (N) utilisation in mustard (Brassica juncea L. Czern & Coss.). Mustard has a high sulfur (S) requirement. Its assimilatory pathway is well coordinated with N and dependent on photosynthesis. Thus, the higher photosynthate production and an efficient use of N with the use of GA3 could result in an increase in S-use efficiency of the crop. The research was, therefore, carried out to study the effects of 10~μM GA3 spray on specific leaf area, plant dry mass, leaf carbon dioxide exchange rate (CER), plant growth rate (PGR), relative growth rate (RGR), net assimilation rate (NAR) and S-use efficiency (SUE) of mustard treated with 0, 100 or 200 mg S kg−1 soil levels. Plants treated with 100~mg S kg−1 soil and receiving GA3 treatment showed increased specific leaf area and dry mass accumulation compared to the control. At 0~mg S kg−1 soil, N and S concentrations were reduced. They increased with increasing S supply. GA3 application significantly increased N and S concentrations further. A two-fold increase in SUE in GA3-treated plants at 100~mg S kg−1 soil was noted in comparison to the control. SUE was not increased under excess S conditions beyond 100~mg S kg−1 soil. The increase in SUE was through increase in the growth, CER and use efficiency of N by the crop due to GA3 application.

Alleviation of frost damage to pear flowers by application of gibberellin

Adverse effects of gibberellin applications on pear trees after frost such as small fruit size, abnormal fruit shape and poor return bloom are often attributed both to the sole use of GA3 and its overdose. It is unclear whether protection against spring frosts before flower opening is more efficient when GA is applied directly after frost, i.e. before flower opening, or at full bloom or both. In April 2003, early spring frosts at Klein-Altendorf near Bonn, Germany damaged ca. 88% flowers of the early flowering cv. Alexander Lucas, 64% of cv. Conference and ca. 25% of flowers of the later flowering cv. Comice pears. Hence, the objective of the present work was to investigate the optimum timing of the application of low doses of the combined GA3 and GA4 + 7 to improve parthenocarpic fruit set in pears, while maximising fruit quality and size for trees affected by a severe spring frost before full bloom. Return bloom was also considered and quantified. Frost-affected pear trees were treated with gibberellin GA3+GA4 + 7, either immediately after the frost, at the white bud stage, or at full bloom or both to improve parthenocarpic set. Early flowering cv. Alexander Lucas pear was most affected by the early spring frost, but lost only 25% of fruitlets at June drop, irrespective of GA treatment. June drop was, however, severe in the two other cultivars least affected by frost, i.e. by 33% in cv. ‘Conference’ and 55% in cv. Comice. Both initial and final fruit set were significantly increased by a combined application of GA3+GA4 + 7 at full bloom, without affecting return bloom, but June drop was also enhanced by GA application. The largest positive effect of GA application on fruit yield, an additional 2 kg of fruit per tree equivalent to €1200/ha, was apparent with the cv. Alexander Lucas, i.e. the cultivar most affected by frost. There was no loss in fruit quality viz fruit size after any of the GA applications with any of the pear cultivars examined and no increase in abnormally-shaped, elongated fruit.

Crescimento de plantas micropropagadas de macieira em casa de vegetação com aplicações de ácido giberélico

O objetivo deste trabalho foi otimizar o crescimento de plantas micropropagadas do porta-enxerto de macieira 'Marubakaido' (Malus prunifolia) em casa de vegetação, por meio da aplicação de ácido giberélico (AG3) por uma, duas, ou três vezes, em intervalos semanais. As concentrações testadas foram: 0, 50, 100, 200, 400, 800 e 1.600 mg L-1. O crescimento das plantas foi avaliado quinzenalmente, por um período de dois meses. O comprimento dos entrenós e a matéria seca da parte aérea das plantas também foram avaliados no final do experimento. Três aplicações de AG3 na concentração de 800 mg L-1 foi o tratamento que proporcionou a maior taxa de crescimento das plantas (912% contra 114% das plantas não-tratadas), além de proporcionar plantas com maior comprimento de entrenós e massa seca da parte aérea. Plantas pulverizadas uma única vez não apresentaram diferenças significativas em nenhuma das variáveis estudadas. Estes resultados sugerem que o uso do AG3 em plantas de macieira, oriundas da micropropagação, melhora o crescimento, embora um número de pelo menos três aplicações, associado com concentrações mais elevadas, seja necessário para melhorar a eficiência deste regulador.